/**
 * What is a palindrome? https://en.wikipedia.org/wiki/Palindrome
 * Receives a string and returns whether it can be rearranged to become a palindrome or not
 * The string can only be a palindrome if the count of ALL characters is even or if the ONLY ONE character count is odd
 * Input is a string
 *
 **/

const palindromeRearranging = ( str ) => {
  // check that input is a string
  if ( typeof str !== 'string' ) {
    return 'Not a string'
  }
  // Check if is a empty string
  if ( str.length === 0 ) {
    return 'Empty string'
  }

  // First obtain the character count for each character in the string and store it in an object.
  // Filter the object's values to only the odd character counts.
  const charCounts = [ ...str ].reduce( ( counts, char ) => {
        counts[ char ] = counts[ char ] ? counts[ char ] + 1 : 1
    return counts
  }, {} )
  // If the length of the resulting array is 0 or 1, the string can be a palindrome.
  return Object.values( charCounts ).filter( count => count % 2 !== 0 ).length <= 1
}

// testing
console.log( palindromeRearranging( 'aaeccrr' ) ) // true
console.log( palindromeRearranging( 'leve' ) ) // false
